The invention relates to a plug for closing battery cells, having an essentially cylindrical housing which can be inserted into an opening of the cell, is open at the bottom and whose upper opening can be closed by a lid.
In batteries for motor vehicles the accumulator cells are closed by a plug which is screwed into the opening of the cell by means of a thread. A screw plug of this type is entirely adequate, since in these batteries the level of the liquid electrolyte need only be checked occasionally. In contrast, more powerful batteries (heavy-duty accumulators) must be checked and topped up at substantially shorter intervals. Accordingly for the more powerful batteries plugs of the design outlined above are used whose upper openingxe2x80x94the checking and top-up openingxe2x80x94can be closed by a lid. This facilitates checking of the level, which is required at short intervals. However, it is disadvantageous that high-capacity batteries must be topped up very frequently, depending on their operational purpose, in many cases even daily, in order to compensate for the loss of liquid in the cell.
The invention is based on the object of providing a battery plug of the specified generic type, which is designed in such a manner that the evaporating liquid rising out of the cell is caught by simple means and returned back into the cell, with the result that checking and topping up can be carried out at substantially longer intervals.
According to the invention, this object is achieved in the case of a plug of the specified design by a collecting element for receiving rising and condensed gases being arranged in the region of the upper opening of the housing .
Since this collecting element is provided in the upper region of the plug, where temperatures are lower than in the underlying zones, the condensing of the rising gas is assisted, so that the liquid can be collected here and passed back into the cell.
The collecting element has a multiplicity of pins which protrude downward from a cover of the collecting element. The plurality of pins provides a very large surface area for the condensation. The pins allow the condensed liquid to drip downward and returned into the cell.
It is particularly advantageous if the collecting element consists of a labyrinth insert which has a cover which is interspersed with holes and from which the pins downwardly flood. The labyrinth insert can be fastened to the inside of the lid with a snap fit or in another manner, or else can be of integral design with the lid.
It has proven particularly advantageous in practice if, with the lid closed, the labyrinth insert forms, with its lower edge, a seal with respect to the inner wall of the housing, and between its cover and the insert of the lid bounds a flat clearance space which is connected via lateral passage openings to an annular space between the labyrinth insert and the inner wall of the housing, which inner wall has a degassing opening.
In this embodiment, the rising gases which are produced during operation in the plug housing initially sweep past the pins, where the condensing liquid precipitates. The gases then pass through the holes in the cover into the flat clearance space, where condensing gas is once again retained. The gases, which are virtually completely dehumidified, then pass via the lateral passage openings into the annular space and can escape from there to the outside by way of the degassing opening.
Battery plugs of the described design, which are provided for manual topping up of liquid, generally have a holder which is tapered conically downward, is inserted from above into the opening of the housing and protrudes downward as a small holder of smaller diameter. In the fitted state of the plug the lower end of the smaller holder is not intended to stand on the accumulator plates, it is merely intended to facilitate the checking and topping up. The smaller holder, which protrudes downward from the bottom of the conically tapered holder, serves mainly as an indicating element for the necessary filling height. During a check it can easily be established whether the filling level lies at the height of the open bottom of the holder, from which the small holder of lower diameter protrudes downward. However, since the distance between the upper periphery of the accumulator plates and the opening of the cell differs in different types of battery, a multiplicity of holders have to be kept ready in order to accommadate these dimensional differences.
In order to solve this problem in the case of a battery plug according to the invention, provision is made for the holder to be held by its upper edge in the housing in a longitudinally adjustable manner. In this case, it is preferred to fix the holder by its upper edge in the housing in an infinitely adjustable manner by means of frictional engagement against the inner wall of the housing. Radially resilient barbs and latching studs, which ensure the frictional engagement between the holder and housing, can protrude from the upper edge of the holder.
It is therefore possible to keep a standard holder ready for all sizes of battery, the holder being pulled out as far as possible before the plug is inserted into the cell opening. During the subsequent insertion into the cell opening the small holder is supported with its lower end on the upper side of the plates of the cell and is displaced relative to the housing until the latter has been completely inserted into the opening of the cell lid.
Height compensation, which may be necessary due to thermal expansion of the accumulator plates during operation, is provided as a consequence of the frictional engagement between the housing wall and barbs.
In another embodiment of the invention, the inner wall of the housing has latching sockets lying axially one above another on one side, for the snap-action engagement of the latching studs. This makes it possible to establish predetermined, specified positions for the position of the holder, which positions are suitable for most commercially available designs.
In the invention it is possible to insert the holder, rotated through 180xc2x0, into the housing, so that in a first position the latching studs engage in the latching sockets, while in the second position rotated through 180xc2x0, the latching studs do not engage in the latching sockets and bear in a frictionally engaged manner against the inner wall of the housing in order for the holder to be infinitely adjusted.
The various features of novelty which characterize the invention are pointed out with particularity in the claims appended to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects obtained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.